Diverse and varied brewing techniques have for many years been proposed or practiced with a view to producing low-alcohol beers or non-alcoholic malt beverages. For the present purposes, "beer" is a malt-beverage product having an alcohol content in the range of three to five and one half percent, on a volume basis. "Low-alcohol beer" is herein distinguished from "beer" on the basis of their respective alcohol contents, with the former's being in the range of one to three percent, also on a volume by volume basis. "Non-alcoholic malt beverages" on the other hand have alcohol contents that are equal to or less than one half of one percent, (again on a volume by volume basis).
Although efforts to produce alcohol-reduced malt beverages are hardly a recent phenomenon, socially responsible consumption and general health awareness have renewed interest in the possibilities of such products. The historical difficulty of achieving acceptable consumer taste profiles at manageable capital and production cost persists, however, as the principle hurdle to acceptance of products of this type.
Prior efforts have included the use of yeasts that lack the ability to ferment certain sugars (such as Sacch. ludwigii, for example); interrupted fermentation techniques; high temperature mashing techniques; the "Barrel system"; alcohol rectification, including distillation, evaporation, reverse osmosis, and dialysis techniques. These processes have resulted in products of limited commercial success. Such historical approaches to alcohol reduction or repression of alcohol production, have adversely affected taste profiles or involved high capital or energy costs, or limited production throughputs.
Cold contact processes have also been utilized in the production of non-alcoholic beverages. Japanese Kokai 53-127861, for example, discloses a process in which a wort of fifteen to twenty-five percent Balling, at low temperatures (between minus five and ten degrees Centigrade, and preferably between two and minus two degrees Centigrade), is contacted with one and one-half to two weight percent of yeast, for a period of between sixteen and seventy-two hours. The yeast is removed, and the beverage is finished through dilution with water to achieve the desired alcohol content; carbonation; and acidification with lactic acid to sharpen the inherently sweet taste which is often characteristic of products of this and other cold-contact processes.
Another cold contact process is described in U.S. Pat. Nos. 4,661,355 and 4,746,518, according to which a dilute, (six to twelve percent solids), acidified wort, (pH of about 4), is contacted with an alcohol-free yeast for about twenty-four to forty-eight hours at a temperature of below zero degrees Centigrade. Yeast separation and carbonation follow, to produce a beverage having only a nominal alcohol content.
Yet another cold contact process is described in published Canadian Patent Application 2,027,651. That publication describes a process for producing a non-alcoholic malt beverage. The process entails contacting a slurry containing at least ten percent yeast suspended in fresh regular green beer, with a wort having fourteen to twenty percent extract by weight. The wort and slurry are mixed in the necessary relative proportions to produce a yeast cell count of not less than one hundred million cells per milliliter of mixture. Note that the patentee originally taught that concentrations of one hundred and thirty million cells per milliliter were essential to the process, only to later discover that the minimum could be pushed to as low as the one hundred million cells now taught as the minimum amount essential for the purposes of that process. Contact is sustained at temperatures of between three and seven and one half degrees Centigrade for a period of between one half and ten hours. The beverage is finished through carbonation and dilution to reduce the alcohol content to meet the non-alcoholic specification.
U.S. Pat. No. 4,971,807 discloses another process for producing a low alcohol content beer in which process a relatively small amount of ascorbic acid is added to the wort. The wort is then boiled or heated at a temperature of above 80 degrees Centigrade, for at least half an hour, during which time the ascorbic acid reacts to eliminate bitter after-taste producing substances that are oxidation products arising out of the malt roasting process. The ascorbic acid according to this patented process is substantially eliminated during this reaction, and hence has no other effect on the wort. It may be noted that adding ascorbic acid without heating is stated by the patentee to be ineffective.